Aluminium and titanium

extraction of aluminium

cryolite is added to alumina to lower the melting point and save energy.

the lining of the steel tank is made from carbon which acts as the negative electrode.

aluminium ions are reduced to form molten aluminium Al3+3e- —> Al

the molten is then drained off and cast into ignots

the positive electrodes are made from carbon, oxidised to form oxygen gas 2O2- —> O2+4e-

carbon electrodes are replaced regulary as they react with oxygen as it forms.

titanium

its rutile and contains titanium dioxide.

titanium has similar reactivity to aluminium but is not extracted by electrolysis as it forms crysals and lead to impurities.

extraction of titanium

kroll process:

titanium dioxide, coke and chlorine are heated together at about 900 degrees to form titanium chloride TiO2(s) + 2C(s) + 2Cl 2(g) —> TiCl4(g) + 2CO(g)

magnesium is used as a reducing agent to form titanium Ticl4(g) + 2Mg(l) —> Ti(s) + 2MgCl2(l)

whats bad about extraction of titanium

the process is expensive due to large amounts of energy needed to create the very high temperatures involved

the magnesium thats used in the process is produced by energy intensive electrolysis process its a time consuming process the reactor has to be shut down and cooled down before titanium can be removed for purification the i purities also gace to be removed by further hearting

factors of aluminium

strong

light weight

rigid

high resistancer to corrosive

cheap

factors of titanium

high resistance to corrosive

dense

strong